Vinasse processing by electrodialysis combined with nanofiltration: emphasis on process optimization and environmental sustainability.

Vinasse, due to its high organic load, low pH, high corrosivity, and high potassium levels, can cause salinization, acidification, loss of fertility, and leaching of constituents when applied to agricultural soils. In this context, electrodialysis (ED) was used to remove potassium from this effluent, to concentrate it in the cathode concentrate compartment. The cathode concentrate was subjected to nanofiltration (NF), allowing the electrolyte to be reconditioned and simultaneously generating a solution rich in potassium, making it an input for the fertilizer industry. The conditions of NF were optimized by the design of experiments. The optimal conditions obtained were 6 bar pressure, 1.8 L min-1 flow, and 1.6× feed dilution factor. Although the reconditioned electrolyte has been feasible, the raw vinasse (pre-ultrafiltered) was compared and proved to be a sustainable option. The NF permeate had a potassium concentration of 90% and magnesium of 84%, in addition to the annual reduction in magnesium sulfate demand (139,450,988 kg) and distilled water (5,019 m3). It was also possible to obtain an increase of approximately 400% in the rate of the application of vinasse in fertigation without compromising the needs of the plantation, the quality of the soil, and groundwater.

Influence of humic substances on the landfill leachate biodegradability with a focus on temporal seasonality.

The high resilience to biological treatments from the landfill leachate is generally associated with the presence of humic substances (HS). The brown color characteristic of this effluent is also related to these substances. Landfill leachate with low biodegradability can make biological treatments unfeasible, which can drive up the cost for the treatment of large leachate volumes. In this context, this research aimed to characterize the leachate in different seasonal periods, and verify the influence of HS species on the biodegradability of the effluent to assist in the selection of adequate treatment techniques. The HS quantification was performed using the modified Lowry method and speciation through fractionation according to the molar masses of the HS species. The tropical regions can be the precursor for the rapid stabilization of biodegradable organic matter. The warmer climate contributed to a reduced BOD/COD ratio (0.03) and the predominance of compounds of lower mass (e.g.: fulvic acids). The tests showed an HS concentration of 26.9% of the total COD in the raw leachate in the rainy season, which increased to 37.3% in the dry season. Approximately 70% of HS species refer to fulvic acids, a fraction identified as having the highest biologic treatment resilience.

Hybrid MF and membrane bioreactor process applied towards water and indigo reuse from denim textile wastewater.

This work investigates the application of a microfiltration (MF)-membrane bioreactor (MBR) hybrid process for textile dyeing process wastewater reclamation. The indigo blue dye was efficiently retained by the MF membrane (100%), which allows its recovery from the concentrate stream. MF promotes 100% of colour removal, and reduces the chemical oxygen demand (COD) and conductivity by about 65% and 25%, respectively, and improves the wastewater biodegradability. MF flux decline was mostly attributed to concentration polarization and the chemical cleaning was efficient enough to recover initial hydraulic resistance. The MBR provides to be a stable process maintaining its COD and ammonia removal efficiency (73% and 100%, respectively) mostly constant throughout and producing a permeate that meets the reuse criteria for some industry activities, such as washing-off and equipment washdown. The use of an MF or ultrafiltration (UF) membrane in the MBR does not impact the MBR performance in terms of COD removal. Although the membrane of MBR-UF shows permeability lower than MBR-MF membrane, the UF membrane contributes to a more stable operation in terms of permeability.

Avaliação da microfiltração para remoção do lodo gerado no processo oxidativo avançado empregando o reagente de Fenton no tratamento de lixiviado de aterro sanitário / Evaluation of microfiltration for removal of sludge generated in advanced oxidation process by Fenton reagent in treatment of landfill leachate

Uma alternativa atrativa para o tratamento de lixiviado de aterro sanitário são os processos oxidativos avançados empregando o reagente de Fenton (POA/Fenton). No entanto, a aplicação do POA/Fenton é limitada pela geração de lodo no processo. Esse lodo possui elevada concentração de ferro, o que torna necessária sua separação do efluente tratado. O objetivo desse trabalho foi avaliar a microfiltração para a remoção de lodo gerado no POA/Fenton. A pesquisa foi desenvolvida em unidade de bancada. O POA/Fenton apresentou elevada eficiência na remoção de matéria orgânica (75 por cento) e cor real (95 por cento). O processo de microfiltração foi eficiente na separação do lodo gerado, o qual apresentou baixa sedimentabilidade, dificultando sua separação por sedimentação, além de ter contribuído para a remoção de outros poluentes.

Advanced oxidation processes using Fenton's reagent (AOP/Fenton) are an attractive alternative for landfill leachate treatment. However, the implementation of the AOP/Fenton is limited by the generation of sludge in the process. The sludge has a high iron concentration, which needs its separation from the treated effluent. The aim of this study was to evaluate the microfiltration for sludge removal from an AOP/Fenton. The work was conducted in bench scale. The advanced oxidation process showed high efficiency in removing organic matter (75 percent) and true color (95 percent). The microfiltration was effective in separating the sludge, which showed low settling hindering their separation by sedimentation, and has contributed to the removal of other pollutants.